In recent years, a gas turbine power generating equipment generating several tens to several hundreds kW and using a radial turbine as a gas turbine for driving a generator is under consideration. As a means for enhancing power generation efficiency in such a gas turbine power generating equipment, it is cited to increase turbine inlet temperature. However, if the turbine inlet temperature is increased, particularly a turbine nozzle and the like reach a high temperature, which may cause a situation where those materials or the like are melted. As one countermeasure against it, there is a method of reducing the metal temperature by cooling the turbine nozzle using air at lower temperature/higher pressure than the gas in a turbine inlet portion. An example of the structure to which such a cooling method is applied is disclosed in JP-U-62-135802. In this prior art, the cooling air which cools the nozzle of the radial turbine diverges, so that one of the airs is released outside after passing through the inside of a nozzle blade, and the other of the airs is sprayed to the nozzle from an upstream side of a combustion gas flow path to cool the nozzle.